Mellanox ConnectX-4 VPI Adapter Card (MCX455A-ECAT)

The Mellanox ConnectX-4 Virtual Protocol Interconnect (VPI) adapter card provides a high-performance, flexible interconnect solution for High-Performance Computing (HPC), enterprise data centers, Web 2.0, cloud, and storage platforms. Featuring a single QSFP28 port, it supports 100 Gb/s EDR InfiniBand or 100 Gb/s Ethernet connectivity dynamically on the same hardware.

1. Product Identification

• Model / Part Number: MCX455A-ECAT

• Family: Mellanox ConnectX®-4 VPI

• Bracket/Form Factor: Low Profile (LP) PCB board size — Often designated with (FH) for the Pre-installed Full-Height / Tall bracket, but interchangeable with an LP bracket.

• Controller ASIC: Mellanox / NVIDIA MT27704A0-FDCF-EV

2. Technical Specifications

Feature	Specification
Interface / Bus Type	PCI Express (PCIe) 3.0 x16 (Backward compatible with PCIe 1.1 / 2.0)
Bus Transfer Rate	8.0 GT/s per lane (effective bandwidth up to ~128 Gb/s)
Port Configuration	Single-Port (1x) QSFP28 (Quad Small Form Factor Pluggable 28)
Network Protocols	Dual-Protocol support: EDR InfiniBand or 100GbE Ethernet
Supported Data Rates	InfiniBand: SDR, DDR, QDR, FDR, EDR Ethernet: 10 / 25 / 40 / 50 / 100 Gb/s
Cabling Support	Passive copper cables (DAC), active copper cables (ACC), and active optical cables (AOC)
Physical Dimensions	2.71 in. x 5.6 in. (68.90 mm x 142.24 mm) – standard MD2 Low-Profile profile

3. Advanced Features & Offloads

Virtual Protocol Interconnect (VPI)

Allows any standard networking, clustering, or storage protocol to operate seamlessly over a single interconnect cable. The port can be configured dynamically as InfiniBand or Ethernet.

High-Performance Networking & Storage Offloads

• RDMA Engine: Native InfiniBand RDMA and RoCE v1/v2 (RDMA over Converged Ethernet) with sub-microsecond latency and kernel bypass.

• Hardware Offloads:

  • Stateless offloads (RSS, LSO, TSO, TX/RX Checksum).

  • Encapsulation protocol offloads for Virtualized Overlay Networks: VXLAN, NVGRE, GENEVE, and MPLS.

  • Connection Tracking (CT) offload.

• Mellanox PeerDirect®: Facilitates high-efficiency direct communication between GPUs and the network card (GPUDirect RDMA) to bypass host CPU overhead.

• T10-DIF Signature Handover: Hardware offload for end-to-end data integrity protection, critical for high-end enterprise storage networks.

• Packet Rate: Up to 150 million messages per second capability.

Virtualization (SR-IOV)

• Supports hardware-based I/O virtualization.

• Single Root I/O Virtualization (SR-IOV) supporting up to 128 Virtual Functions (VFs).

4. Hardware Components & Standards

• Onboard Memory: Includes one 16MB SPI Flash device (M25PX16) for firmware storage.

• Compliant Standards:

  • IEEE: 802.1Q, 802.1p, 802.3ad (LACP), 802.3ae, 802.3ap, 802.3az, 802.3ba, 802.1ax, 802.1qbb, 802.1qaz, 802.1qau, 802.1qbg, 1588v2 (PTP).

  • InfiniBand Association: IBTA v1.3 compliant.

  • Environmental: RoHS compliant.

5. Driver & Operating System Support

Recognized by modern kernels as the standard mlx5_core driver:

• Linux: NVIDIA/Mellanox OFED (MLNX_OFED) and Linux In-Box drivers.

• Windows: WinOF-2 driver.

• VMware: ESXi (nmlx5 native driver).